Influence of Viscoelastic Dampers on the Seismic Response of a Lightly Reinforced Concrete Flat Slab Structure

1999 ◽  
Vol 15 (4) ◽  
pp. 681-710 ◽  
Author(s):  
John R. Hayes ◽  
Douglas A. Foutch ◽  
Sharon L. Wood
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Horizontal Displacement ◽  
Shaking Table ◽  
Scale Model ◽  
Earthquake Simulation ◽  
Flat Slab ◽  
Viscoelastic Dampers ◽  
Seismic Rehabilitation ◽  
Lightly Reinforced Concrete

A 1/3-scale model of a section of a three-story lightly reinforced concrete flat slab structure was constructed. Researchers installed a viscoelastic damper (VED) seismic rehabilitation system on the model and subjected it to seismic simulations on a shaking table. Successive simulations were conducted with increasing base accelerations until the horizontal displacement limit of the shaking table was reached. The dampers were then removed, and the simulations were repeated until structural failure occurred. This paper summarizes the responses of the model. Brief comparisons of the responses of the model with and without VEDs installed are made. The VEDs improved energy dissipation characteristics and serviceability of the structure by reducing interstory displacements. Earthquake simulation responses indicated that the damper configuration that was employed in the experimental investigation permitted rotations of the VEDs, which lowered their energy dissipation efficiency. An alternate arrangement for the VEDs is proposed to alleviate this problem.

Inelastic Response of R/C Structures with Viscoelastic Braces

1993 ◽  
Vol 9 (3) ◽  
pp. 419-446 ◽  
Author(s):  
R. F. Lobo ◽  
J. M. Bracci ◽  
K. L. Shen ◽  
A. M. Reinhorn ◽  
T. T. Soong
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Concrete Structures ◽  
Elastic Stiffness ◽  
Shaking Table ◽  
Reinforced Concrete Structures ◽  
Inelastic Response ◽  
Viscoelastic Dampers ◽  
Stiffness Properties ◽  
Scaled Models

The addition of viscoelastic braces in structures for vibration reduction has been proposed and implemented in the past decade in metal scaled models of full-scale structures. Viscoelastic braces can provide energy dissipation, while the structure remains elastic. In reinforced concrete structures, the seismic response is usually inelastic, which is often accompanied by permanent deformations and damage. The addition of viscoelastic dampers can dissipate energy at the early stages of cracking of the concrete elements and reduce the development of damage. With proper selection of dampers, this damage can be substantially reduced or even eliminated. However the addition of viscoelastic dampers may stiffen the structure unnecessarily producing increased inertial forces and base shears when subjected to seismic motion. The quantification of the influence of viscous damping and elastic stiffness properties of dampers during the inelastic response of reinforced concrete structures is the subject of this investigation. Models for analysis of inelastic response with damage indexing for reinforced concrete structures that include viscoelastic braces are developed and calibrated using experimental data produced by shaking table tests. These models are then used to determine the variation of expected damage in the presence of damping and quantify the hysteretic energy dissipation along with the damping energy.

Seismic Rehabilitation of Beam-Column Joints Using FRP Sheets and Buckling Restrained Braces

2013 ◽  
Vol 479-480 ◽  
pp. 1170-1174
Author(s):  
Hee Cheul Kim ◽  
Dae Jin Kim ◽  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Seismic Performance ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Seismic Rehabilitation ◽  
Buckling Restrained Braces ◽  
Column Joint ◽  
Energy Dissipation Capacity

The purpose of this study was to evaluate seismic performance of rehabilitated beam-column joint using FRP sheets and Buckling Restrained Braces (BRBs) and provide test data related to rehabilitated beam-column joints in reinforced concrete structures. The seismic performance of total six beam-column specimens is evaluated under cyclic loadings in terms of shear strength, effective stiffness, energy dissipation and ductility. The test results showed wrapping FRP sheets can contribute to increase the effect of confinement and the crack delay. Also retrofitting buckling restrained braces (BRBs) can improve the stiffness and energy dissipation capacity. Both FRP sheets and BRBs can effectively improve the strength, stiffness and ductility of seismically deficient beam-column joints.

scholarly journals Seismic Behavior of Concrete-Filled Circular Steel Tubular Column–Reinforced Concrete Beam Frames with Recycled Aggregate Concrete

2020 ◽  
Vol 10 (7) ◽  
pp. 2609 ◽  
Author(s):  
Zongping Chen ◽  
Ji Zhou ◽  
Zhibin Li ◽  
Xinyue Wang ◽  
Xingyu Zhou
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Seismic Behavior ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Scale Model ◽  
Hysteresis Curve ◽  
Small Scale ◽  
Skeleton Curve ◽  
Aggregate Concrete

The application of recycled aggregate concrete (RAC) in concrete filled steel tubular (CFST) structures can eliminate the deterioration of concrete performance caused by the original defects of the recycled aggregate, which also provides an effective way for the recycling of waste concrete. In this paper, a test of a small scale model of a circular CFST column-reinforced concrete (RC) beam frame with RACs under low cyclic loading was presented in order to investigate its seismic behavior. The failure modes, plastic hinges sequence, hysteresis curve, skeleton curve, energy dissipation capacity, ductility and stiffness degeneration of the frame were presented and analyzed in detail. The test results show that the design method of the recycled aggregate concrete filled circular steel tube (RACFCST) frame complies with the seismic design requirements of a stronger joint followed by the stronger column and the weaker beam. The hysteresis curve of the frame is symmetrical, showing a relatively full shuttle shape; at the same time, the ductility coefficient of the frame is greater than 2.5, showing good deformation performance. In addition, when the frame is damaged, the displacement angle is greater than 1/38, and the equivalent damping ratios coefficient is 0.243, which indicates that the frame has excellent anti-collapse and energy dissipation abilities. In summary, the RACFCST frame has good seismic behavior, which can be applied to high-rise buildings in high-intensity seismic fortification areas.

Shaking Table Tests of a Typical Mexican Colonial Temple: Evaluation of Two Retrofitting Techniques

2013 ◽  
Vol 29 (4) ◽  
pp. 1209-1231 ◽  
Author(s):  
Marcos Chávez ◽  
Roberto Meli
Keyword(s):  
Energy Dissipation ◽  
Research Program ◽  
Maximum Intensity ◽  
Shaking Table ◽  
Scale Model ◽  
Stone Masonry ◽  
Significant Source ◽  
Second Phase ◽  
Shaking Table Tests ◽  
Displacement Capacity

This paper reports the results of the second phase of a research program that carried out shaking table tests on a scale model of a typical stone masonry temple. This second phase evaluates the efficacy of two different retrofitting techniques by comparing the response of the retrofitted models with that of the original unreinforced model. It was found that both retrofitting schemes substantially enhanced the performance of the model temple. The maximum intensity of the base motion for which damage was considered to be still repairable increased by 80% and 120% for the first and the second levels of retrofitting, respectively. In terms of displacement capacity, the response of the model with the second level of retrofit reached a maximum drift of 0.4%. The initial damping ratios were found to be in the range of 7% to 9%, both in the original and the retrofitted models. These ratios constitute a significant source of energy dissipation for this kind of structure.

The Seismic Response of a 1:3 Scale Model R.C. Structure with Elastomeric Spring Dampers

1995 ◽  
Vol 11 (2) ◽  
pp. 249-267 ◽  
Author(s):  
Gokhan Pekcan ◽  
John B. Mander ◽  
Stuart S. Chen
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Structural Response ◽  
Time History ◽  
Shaking Table ◽  
Frame Structure ◽  
Scale Model ◽  
History Analysis ◽  
Analysis Computer ◽  
Dynamic Time

In this experimental study, elastomeric spring dampers, which have a distinct re-centering characteristic, are used to retrofit a non-ductile, previously damaged 1/3 scale model reinforced concrete building frame structure which is subjected to a variety of ground motions in shaking table tests. A velocity dependent analytical model is developed and verified for the elastomeric spring dampers. This model is implemented in the widely available non-linear dynamic time history analysis computer program DRAIN-2DX to produce response predictions which are in good agreement with experimental observations. The elastomeric spring damper devices significantly attenuate the seismic response of the structure and provide a considerable amount of energy dissipation while the main non-ductile reinforced concrete structural load carrying elements remain elastic. The effect of varying the damper configuration on the structural response was also investigated.

Characteristics of Earthquake Damage for High Core and Concrete-Faced Rock-Fill Dams by Shaking Table Tests

2013 ◽  
Vol 680 ◽  
pp. 194-199
Author(s):  
Lin Juan Yuan ◽  
Xiao Sheng Liu ◽  
Xiao Gang Wang ◽  
Chen Dai
Keyword(s):  
Large Scale ◽  
Residual Deformation ◽  
Horizontal Displacement ◽  
Earthquake Damage ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Earthquake Simulation ◽  
Rock Fill ◽  
Downstream Slope ◽  
Before And After

The pattern and characteristics of seismic damage for Shuangjiangkou ECRD and Houziyan CFRD models were studied through large-scale earthquake simulation shaking table tests in this work. The test results showed that the main earthquake damage pattern of rock-fill dam is permanent residual deformation and shallow slide on the downstream slope. Seismic residual deformation of rock-fill dam, which is filled and compacted well, is very small. Regardless of ECRD or CFRD, the horizontal displacement and settlement on downstream slope are significantly larger than upstream slope under empty reservoir. The analysis of residual deformation and vibration frequency before and after failure indicated that aseismic performance of CFRD is superior to ECRD. Because of the remarkable whipping effect in the high rock-fill dam, the key parts of aseismic design is downstream slope near the dam top, where appropriate aseismic measures should be taken.

Shaking Table Tests and Numerical Simulation Analysis of a 1:15 Scale Model Reinforced Concrete Containment Vessel

2013 ◽  
Author(s):  
Xiaolei Wang ◽  
Dagang Lu ◽  
Gangling Hou
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Simulation Analysis ◽  
Safety Margin ◽  
Shaking Table ◽  
Scale Model ◽  
Shaking Table Tests ◽  
Ground Acceleration ◽  
Containment Vessel ◽  
Earthquake Motion

In order to verify the seismic capacity of reinforced concrete containment vessel (RCCV) under the design earthquake level of SL-2 (peak acceleration 0.25g), shaking table tests of a 1:15 model RCCV are carried out. The El Centro earthquake motion record, the Taft earthquake motion record as well as an artificial earthquake acceleration are employed as the input excitations. There are three load cases for each test stage, with the peak ground acceleration (PGA) being 0.1g, 0.2g and 0.3g, respectively, corresponding to 0.088g, 0.175g and 0.263g for the prototype RCCV structure because of the acceleration ratio of 1.14. The test results indicate that under the earthquake excitation of the acceleration peak 0.1g, 0.2g and 0.3g, the tensile strains at monitoring points on the cylinder don’t reach the cracking level. Using the general-purpose nonlinear finite element analysis program ANSYS, a three-dimensional (3D) model of the scaled model reinforced concrete containment vessel is modeled. The numerical simulation analysis results could match the results of the tests very well. It is shown by the results of the shaking table tests that the model RCCV is still within the elastic range as a whole. In order to analyze the yield displacement of the RCCV, a static nonlinear pushover analysis of the RCCV is carried out. The result shows that the RCCV had sufficient seismic safety margin.

Experimental Study on the Effect of Moisture Content on Hysteretic Behavior of Reinforced Concrete Columns

2018 ◽  
Vol 12 (1) ◽  
pp. 47-61
Author(s):  
Wenjuan Lv ◽  
Baodong Liu ◽  
Ming Li ◽  
Lin Li ◽  
Pengyuan Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Moisture Content ◽  
Early Stage ◽  
Damping Ratio ◽  
Concrete Columns ◽  
Hysteretic Behavior ◽  
Cyclic Test ◽  
Experimental Result ◽  
Reinforced Concrete Columns

Background: For reinforced concrete structures under different humid conditions, the mechanical properties of concrete are significantly affected by the moisture content, which may result in a great change of the functional performance and bearing capacity. Objective: This paper presents an experiment to investigate the influence of the moisture content on the dynamic characteristics and hysteretic behavior of reinforced concrete column. Results: The results show that the natural frequency of reinforced concrete columns increases quickly at an early stage of immersion, but there is little change when the columns are close to saturation; the difference between the natural frequencies before and after cyclic test grows as the moisture content rises. The damping ratio slightly decreases first and then increases with the increase of moisture content; the damping ratio after the cyclic test is larger than before the test due to the development of the micro-cracks. Conclusion: The trend of energy dissipation is on the rise with increasing moisture content, although at an early stage, it decreases slightly. According to the experimental result, a formula for the moisture content on the average energy dissipation of reinforced concrete columns is proposed.

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